I agree that Book 4 was much better the 2nd time around. There is a lot going on that you can easily miss the first time because it is hard to see where Martin is going, it has a lot of connection points for later parts of the story. Unfortunately without any Dany or Tyrion who are two of the most interesting characters it really suffers compared to the other books.
You can also tell that Book 6 is going to be the most action packed since Book 3, it has to be. You have the Battle of Ice in the North about to happen, the Battle of Fire in Mereen that has Victorian arriving, Dany meeting up with the Dothraki, Jon Snow's situation, Theon in big trouble, King's Landing about to blow up in a big way with the death of Kevan and Pycelle and the return of Varys combined with Cersei about to go to trial, Arianne going off to meet Young Griff who has landed in Westeros, and Jaime going off with Brienne to meet LSH. That doesn't count Bran or Arya or Sansa or Davos or whatever is happening in Dorne or the WW of course. Most of that will have to be addressed fairly quickly in Book 6. Wouldn't surprise me if Book 6 kills off major characters in a way to make the Red Wedding look tame.